1. Field of Invention
The present invention relates to an electric kettle, and more particularly to a method of water temperature calibration for an electric kettle, which is adapted to accurately determine the temperature of the boiling water in the electric kettle and to cut off the heating power when the water is boiled.
2. Description of Related Arts
The electric kettle has brought many conveniences for people in their living and work. The traditional method for electric kettle to determine and control the boiling water is to apply a “steam” switch made of dual metal materials to switch off the power of the heating source. Accordingly, the amount of steam generated by the boiling water must be enough to trigger the switch so as to cut off the power. In order to guide the steam to communicate with the switch, a steam channel must be additionally formed to let the steam entering into the switch. Therefore, the switch not only complicates the original structural configuration of the electric kettle but also fails to keep the aesthetic appearance of the electric kettle. Importantly, the switch is not sensitive enough to detect the water at the boiling point to cut off the power simultaneously. An alternative calibrating method is to provide a temperature sensor to detect the water temperature such that when the water reaches a preset temperature threshold, the temperature sensor triggers the switch to turn off the power of the heating source. However, the major drawback of the temperature sensor is that the temperature sensor cannot be used when the electric kettle is operated at a location with higher altitude. It is known that the water cannot be reached its boiling point at the high altitude location. Therefore, the heating source will keep heating up the water when the water is boiled. In other words, it is unsafe for the user to operate the temperature sensor type electric kettle at the high altitude location. In addition, such temperature sensor has an error that the temperature sensor cannot accuracy detect the actual water temperature. Therefore, the electric kettle may either boil the water without cutting off the power or cut the power without fully boiling the water.